How do cars waste fuel with warm air in winter?

How do cars waste fuel with warm air in winter?

An automobile engine is a heat engine. Since it is a heat engine, it needs to keep the heat. Where does the heat of the engine come from? Burning fuel to do work is actually closed-loop control!

When the water temperature sensor detects that the engine is in a low temperature state, the ECU of the engine will increase the fuel injection quantity and intake air quantity according to the engine temperature and intake air temperature. At this time, the engine belongs to "rich injection", with more fuel injection and more intake. Obviously, if the temperature in the north is extremely cold to below zero, the engine speed will increase, and some gearboxes will even take the initiative to downshift.

The heat of the warm air actually comes from the radiator of the engine water tank. When the engine D is cold, turning on the warm air at this time will affect the engine heating process. On the one hand, the ECU of the engine should control the engine to heat up, increase the fuel injection, increase the throttle opening and increase the speed. On the other hand, warm air circulation will reduce the water temperature, which is the opposite process. So turning on warm air at low temperature will increase fuel consumption.

In fact, when an experienced old driver drives in the north, he will block the air inlet of half of the water tank with a paper shell to prevent the direct blowing of low-temperature cold air from affecting the engine heating.